JPH0938799A - Method for controlling flow rate of double hydraulic cylinder and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the control by eliminating the overshoot of the actual ram stroke of a small cylinder and to confining the parameters of a large cylinder and the small cylinder to one kind at the same ram speed. SOLUTION: A hydraulic circuit 27 for driving the large cylinder 29 and small cylinder 31 disposed at the double hydraulic cylinders 17 is provided with a servo valve 43 and the step part of a spool 57 disposed at a proportional valve 47 actuated by the pilot pressure of this servo valve 43 is provided with a notched part. The pilot pressure of the servo valve 43 is fixed at the high and low pressure so as to meet the small cylinder 31. The rated flow rate of the servo valve 43 is set at the flow rate of the small cylinder 31 and a flow rate characteristic is changed to shorten the delay time of the small cylinder 31. The control of the large and small cylinders 29, 31 at the same ram speed is made possible without the overshoot of the actual ram stroke of the small cylinder 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling a flow rate of a double hydraulic cylinder, and more particularly to controlling large and small cylinders provided in the double hydraulic cylinder with the same ram speed and the same parameter. And a device for controlling the flow rate of a double hydraulic cylinder.

[0002]

2. Description of the Related Art Conventionally, in a turret punch press, for example, a double cylinder is used as a drive cylinder which is a drive device for reciprocating the punch in order to obtain a high hit rate. When the double cylinder is controlled, the large cylinder and the small cylinder have different masses, and the small cylinder has a low pressure large flow rate and the large cylinder has a high pressure small flow rate, so that the ram speed is changed.

As a hydraulic circuit for operating the double cylinder, for example, the hydraulic circuit shown in FIG. 5 is known.

That is, in the structure of the double cylinder 103 which operates in the hydraulic circuit 101, the small cylinder 107 is incorporated in the large cylinder 105, and the oil chambers 109 and 11 are respectively provided.
1, 113 are formed. Reference numeral 115 is a punch, and reference numeral 117 is a die.

The hydraulic circuit 101 is provided with a variable displacement hydraulic pump 123 driven by a pump motor 121 communicating with the tank 119.
The discharge side pipeline 125 of No. 3 communicates with the P port of the three-position directional control valve 129 which is a servo valve via the check valve 127. When the flow path of the 3-position directional control valve 129 is switched to connect the P port and the A port and the B port and the T port to each other, the pressure oil passes through the pipe 131 and switches the flow path of the 2-position directional control valve 133. When the P port and the B port are communicated with each other and the A port and the T port are communicated with each other, the pressure oil flows into the oil chamber 109 of the small cylinder 107 through the pipe line 135, and the large cylinder 10
5 is lowered.

At this time, the oil in the oil chamber 111 is in the pipeline 1.
It is returned to the tank 119 through the return port 139 from the B port of the 3-position directional control valve 129 through the T port. Further, the oil chamber 113 is in a vacuum state, and the pipeline 141,
Since the oil in the tank 119 is supplied into the oil suction chamber 113 via 143, the large cylinder 105 can be smoothly lowered.

Next, when the flow path of the 2-position directional control valve 133 is switched to connect the P port to the A port and the B port, the oil chamber 109 of the small cylinder 107 and the oil chamber 113 of the large cylinder 105 are more than the P port. The pressure oil flows in to lower the large cylinder 105. The oil in the oil chamber 111 is returned to the tank 119 through the pipe 137, the B port of the three-position directional control valve 129, the T port, and the return pipe 139.

When the flow path of the 3-position directional control valve 129 is switched so that the P port and the B port and the A port and the T port are communicated with each other, the pressure oil is supplied into the oil chamber 111 of the large cylinder 105 through the pipe line 137. , Lift up the large cylinder 105.
Then, the oil in the oil chambers 109 and 113 is transferred to the pipelines 135, 14
1-pass, 2-position directional control valve 133 A, B port P, through a line 131, 3-position directional control valve 1
It is returned from the A port of 29 through the T port to the tank 119 through the return pipe 139. Reference numeral 145 is a pulsation prevention damper, and reference numeral 147 is a filter.

With the above structure, when the small cylinder 107 provided in the double cylinder 103 is driven, the variable displacement hydraulic pump 123 is driven to control the 3-position directional valve 129 which is a servo valve to control the low pressure large flow rate. When the large cylinder 105 is driven, the variable displacement hydraulic pump 123 is driven to drive the three-position directional control valve 129, which is a servo valve.
The ram speed was changed by controlling the high pressure and small flow rate.

[0010]

By the way, the flow control of the conventional double cylinder 103 described above is performed by the large cylinder 10.
5 and the small cylinder 107 have to be controlled separately, and the parameters are also separated, which causes a problem that control becomes very complicated.

More specifically, the conventional double cylinder 103
The flow rate control of the 3-position directional control valve 1 which is a servo valve
However, since the masses of the small cylinder 107 and the large cylinder 105 are different, the inertia moment is also different, and the servo hydraulic rigidity is also different accordingly.

Therefore, if the ram stroke is adjusted before the large cylinder 105 is machined in advance and the ram stroke is switched to the small cylinder 107, the small cylinder 107 is over-shorted as shown in FIGS. 6 and 7. More specifically, the ram stroke of the large cylinder 105 shown in FIG. 6 is shown by the dotted line with respect to the command value shown by the solid line, and the curve is at the actual position. With respect to the actual position of the large cylinder 105, the ram stroke of the small cylinder 107, as shown in FIG. 7, overshoots the actual position indicated by the dotted line with respect to the command value indicated by the solid line at the rising end.

This is because the pilot pressure changes at high pressure and low pressure, and at low pressure using a small cylinder, the pilot pressure decreases and the servo rigidity becomes weak.

The flow rate characteristics are also shown in FIG. 8, and the flow rate W is larger than the input i to the three-position directional control valve 129 which is a servo valve. At 107, different curves are shown.

An object of the present invention is to eliminate the overshoot of the actual ram stroke of the small cylinder and to make the control of the large and small cylinders the same ram speed with one kind of parameter, thereby simplifying the control. A flow control method and an apparatus therefor are provided.

[0016]

In order to achieve the above object, a flow control method for a double hydraulic cylinder according to the present invention according to claim 1 is a flow control method for a large cylinder and a small cylinder provided in a double hydraulic cylinder. Then, the pilot pressure of the servo valve provided in the hydraulic circuit that drives the double hydraulic cylinder is fixed to high and low pressure according to the low pressure that operates the small cylinder, and the pilot rated flow rate of the servo valve is set to the large flow rate of the small cylinder. To change the flow rate characteristics,
The feature is that the delay time of the small cylinder is shortened.

According to a second aspect of the present invention, there is provided a flow rate control device for a double hydraulic cylinder, which is operated by pilot pressure of a servo valve provided in a hydraulic circuit for driving a large cylinder and a small cylinder provided in the double hydraulic cylinder. The stepped portion of the spool provided in the proportional valve is provided with a notch so that the flow rate is increased when the double hydraulic cylinder is raised even when the current to the servo valve is the same when the double hydraulic cylinder is lowered. Is.

Further, a flow rate control device for a double hydraulic cylinder of the present invention according to claim 3 is characterized in that the double hydraulic cylinder is a drive device for reciprocating a punch of a turret punch press.

By using the method and apparatus for controlling the flow rate of the double hydraulic cylinder according to claims 1, 2 and 3 as described above, the pilot pressure of the servo valve is fixed to a low pressure and fixed at a high and low pressure. Servo rigidity becomes uniform with the cylinder. Moreover, since the pilot rated flow rate of the servo valve is matched with the large flow rate of the small cylinder, the flow rate characteristics of the large and small cylinders can be made uniform. Furthermore,
Change the flow rate characteristics to shorten the delay time of the small cylinder.
Thus, it is possible to control large and small cylinders with the same ram speed and the same parameters.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As a machine tool having a double hydraulic cylinder, for example, a turret punch press was adopted in the example of the present embodiment, but the machine tool is not limited to this model, and a double hydraulic cylinder used in all machines is used. It is intended for cylinders.

Referring to FIG. 4, the turret punch press 1 is provided with a gate-shaped frame 3, which is a lower base 5, a side frame 7 standing on the lower base 5, and a side frame 7. And an upper frame 9 provided on the upper part of the.

A rotatable lower turret 11 is supported on the lower base 3, and a plurality of dies D are mounted on the circumference of the lower turret 11 at appropriate intervals. A rotatable upper turret 13 is supported on the upper frame 9 corresponding to the lower turret 11, and a plurality of punches P are mounted on the upper turret 13 at a position corresponding to the die D.

FIG. 6 of the lower and upper turrets 11 and 13.
, The position of the die D and the punch P mounted on the right side is the processing position.
A striker 15 is provided on the upper frame 9 above and below so as to be vertically movable. The striker 15 is connected to a double hydraulic cylinder 17 provided in the upper frame 9 via a ram 19, for example.

At the right end of the lower base 5 in FIG. 4, a carriage base 21 movable in the Y-axis direction (left and right direction in FIG. 4) is provided. The carriage base 21 is in the X-axis direction. A carriage 23 that is movable in the direction (perpendicular to the paper surface in FIG. 4) is provided. The carriage 23 is provided with a plurality of work clamps 25 that clamp the work W at appropriate intervals in the X-axis direction.

With the above construction, by moving the carriage base 21 in the Y-axis direction and the carriage 23 in the X-axis direction, the work W clamped by the work clamp 25 provided on the carriage 23 is moved along the X-axis and the Y-axis. The workpiece W is moved in the direction, and the desired position of the work W is positioned at the processing position.

With the desired position of the work W positioned at this machining position, the upper and lower turrets 13, 11 are placed.
Is rotated to index and position the desired punch P and die D at the processing position. Then, the double hydraulic cylinder 17 is driven to move the striker 15 up and down via the ram 19, whereby the punch P and the die D cooperate with each other.
A normal punching process is performed at a desired position of the work W.

Next, the hydraulic circuit 27 for driving the double hydraulic cylinder 17, which is the main part of the embodiment, will be described in detail.

Referring to FIG. 1, in the structure of the double hydraulic cylinder 17, a small cylinder 31 is incorporated into a large cylinder 29, and oil chambers 33, 35 and 37 are formed respectively. Reference numeral 39 is a punch and reference numeral 41 is a die.

The hydraulic circuit 27 for driving the double hydraulic cylinder 17 is provided with a direct-acting two-stage servo valve 43. This direct acting two-stage servo valve 43
2 has the structure shown in FIG. 2 and has a known structure, so a detailed description thereof will be omitted. The members constituting the servo valve 43 are the direct-acting servo valve 45 and the direct-acting servo valve 45. It is configured by combining with a proportional valve 47 which is operated by the pilot pressure of the die servo valve 45. The respective ports (A, B, P, T ports) of the proportional valve 47 are shown in FIG.

More specifically, in the direct-acting servo valve 45, a pilot spool 51 is mounted in a valve body 49 so that the flow path can be switched. A linear motor 53 attached to one end of the pilot spool 51 causes the pilot spool 51 to move. Driven. Further, in the proportional valve 47, a spool 57 is mounted in the valve body 55 so that the flow path can be switched.
The spool 57 is moved by the pilot pressure of the direct-acting servo valve 45 supplied from the flow paths 55A formed at both ends of the spool 57, and the moving amount of the spool 57 is controlled by the direct-acting servo valve 45. Reference numeral 58 is a differential transformer.

Then, the step portion of the spool 57 provided on the proportional valve 47, which is the main portion of the example of the present embodiment, is notched. Small spools are partially formed on both sides of the stepped portion of the spool 57 provided on the valve body 55 of the proportional valve 47. With this shape, even if the input current i is small, the spool 57 can be moved smoothly, a large amount of hydraulic oil can be flown, and a small flow rate can be covered. Further, a chamfered portion of the step portion of the spool 57 or a cutout portion may be provided in the axial direction of the step portion.

Next, the hydraulic circuit 27 will be described in detail.

Referring again to FIG. 1, the hydraulic circuit 27
A variable displacement hydraulic pump 65 that is driven by a pump motor 63 that communicates with the tank 61 is provided, and a discharge side conduit 67 of the variable displacement hydraulic pump 65 is P of the direct-acting two-stage servo valve 43. It communicates with the port. And
An accumulator 69 is provided in the middle of the discharge side pipe 67, and a pressure reducing valve 71 is provided. An outlet side line 73 of the pressure reducing valve 71 is a servo valve 43 of the direct-acting type servo valve 45. It is connected to the pressure oil inlet. An accumulator 75 is provided in the middle of the outlet line 73.

The set pressure of the pressure reducing valve 71 is, for example, 70% of the main pressure at low pressure. Conventionally, high pressure,
Since the pilot pressures are set individually for the low pressures, separate circuits are required. However, in the example of the present embodiment, only one circuit is required, and the pilot pressures are adjusted to the low pressures and fixed at high and low pressures.

When the flow passage of the direct acting two-stage type servo valve 43 is switched to connect the P port and the A port, and the B port and the T port, the pressure oil passes through the pipe line 77 to the 2-position directional control valve 79. Sent. When the flow path of the 2-position directional control valve 79 is switched to connect the P port and the B port and the A port and the T port to each other, the pressure oil flows through the pipe line 81 into the oil chamber 33 of the small cylinder 31 and the large cylinder 29. To lower.

At this time, the oil in the oil chamber 35 flows through the pipe 83
Through the B port of the servo valve 43, the T port, and the return pipe 85 to the tank 61. Further, the oil chamber 37 is in a vacuum state, and the oil in the tank 61 is supplied into the oil suction chamber 37 through the pipe lines 87 and 89, so that the large cylinder 29 can be smoothly lowered.

Next, when the flow path of the two-position directional control valve 79 is switched to connect the P port to the A port and the B port, the oil chamber 33 of the small cylinder 31 and the oil of the large cylinder 29 are communicated from the P port. The pressure oil flows into the chamber 37, and the large cylinder 2
9 is lowered. The oil in the oil chamber 35 is returned to the tank 61 through the pipe 83, the B port of the servo valve 43, the T port, and the return pipe 85.

The flow path of the servo valve 43 is switched to P
When the port and the B port are communicated with each other and the A port and the T port are communicated with each other, the pressure oil is supplied into the oil chamber 35 of the large cylinder 29 through the pipe 83 to lift the large cylinder 29. Then, the oil in the oil chambers 33 and 37 passes through the pipes 81 and 87, passes through the A and B ports of the two-position directional control valve 79 through the P port, and passes through the pipe 77 to the A port of the servo valve 43 and the T port. And is returned to the tank 61 via the return pipe line 85. Reference numeral 91 is a pulsation prevention damper.

With the above configuration, the pilot pressure for operating the direct-acting servo valve 45 provided in the direct-acting two-stage servo valve 43 is fixed at high and low pressure, for example, 70% of the main pressure at low pressure. Therefore, the large cylinder 29 and the small cylinder 31 have uniform servo rigidity.

Further, the proportional valve 4 provided in the servo valve 43
By forming the cutout portion 59 in the step portion 57A of the spool 57 of No. 7, the movement of the spool 57 becomes smooth even if the input current is small, and a large amount of hydraulic oil can be made to flow, and a small flow rate can be covered.

Since the rated flow rate of the direct acting servo valve 45 is increased to match the large flow rate of the small cylinder 31, the flow characteristics of the large and small cylinders 29, 31 can be made uniform.

That is, as shown by the curve in FIG. 3, the flow rate characteristics are such that the flow rate W becomes the same curve for both the large and small cylinders 29 and 31 with respect to the input i to the direct acting servo valve 45, and the curve descends. Since the mass is large at that time, the flow rate is increased by a small amount of current through only the small cylinder 31 when rising.
If the current is small, the gain can be controlled in a small state and the gain becomes stable. Further, the flow rate characteristic is changed to shorten the delay time of the small cylinder 31.

Thus, the overshoot of the actual ram stroke of the small cylinder 31 is eliminated, and the large and small cylinders 2 are
The 9 and 31 can be controlled at the same ram speed and with the same parameter, and the control can be simplified.

The present invention is not limited to the examples of the above-described embodiments, but can be implemented in other modes by making appropriate changes.

[0045]

As will be understood from the above description of the embodiments, the invention according to claims 1, 2 and 3 is provided in the hydraulic circuit for raising and lowering the double hydraulic cylinder. A proportional valve operated by the pilot pressure of the servo valve was provided, and a cutout portion was formed in the spool step portion of this proportional valve. Therefore, even if the input current is small, the spool can move smoothly, a large amount of hydraulic oil can flow, and a small flow rate can be covered.

Then, the rated flow rate of the servo valve is adjusted to the flow rate of the small cylinder to change the flow rate characteristic to shorten the delay time of the small cylinder, so that the overshoot of the actual ram stroke of the small cylinder is eliminated.

Furthermore, by controlling the pressure reducing valve provided in the hydraulic circuit, the pilot pressure of the servo valve is adjusted to the small cylinder, and the high pressure and low pressure are fixed. Thus, the control can be simplified by using one kind of parameter for the large and small cylinders at the same ram speed.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a main part of the present invention and driving a double hydraulic cylinder.

2 is an enlarged cross-sectional explanatory view of a servo valve provided in the hydraulic circuit in FIG.

FIG. 3 is a graph showing a flow rate characteristic of the double hydraulic cylinder of the present invention.

FIG. 4 is a front explanatory view showing a schematic configuration of a hydraulic turret punch press according to an embodiment of the present invention.

FIG. 5 is a hydraulic circuit diagram for driving a double cylinder, showing a conventional example.

FIG. 6 is a graph showing a stroke of a large cylinder provided in a double cylinder, showing a conventional example.

FIG. 7 is a graph showing a stroke of a small cylinder provided in a double cylinder, showing a conventional example.

FIG. 8 is a graph showing a flow rate characteristic of a double cylinder, showing a conventional example.

[Explanation of symbols]

 1 Turret Punch Press 17 Double Hydraulic Cylinder (Drive Device) 27 Hydraulic Circuit 29 Large Cylinder 31 Small Cylinder 39 Punch 43 Servo Valve 47 Proportional Valve 57 Spool 57A Step 59 59 Notch

Claims (3)

[Claims] 1. A method for controlling a flow rate between a large cylinder and a small cylinder provided in a double hydraulic cylinder, wherein a pilot pressure of a servo valve provided in a hydraulic circuit for driving the double hydraulic cylinder operates the small cylinder. It is fixed to high and low pressure according to low pressure, and the pilot valve flow rate of the servo valve is adjusted to the large flow rate of the small cylinder to change the flow rate characteristics and shorten the delay time of the small cylinder. Flow control method. 2. The double hydraulic cylinder is provided on a stepped portion of a spool provided in a proportional valve which is operated by pilot pressure of a servo valve provided in a hydraulic circuit for driving a large cylinder and a small cylinder provided in the double hydraulic cylinder. The double hydraulic cylinder flow control device is characterized in that the flow control device is provided with a notch so that the flow rate is increased when the servo valve is raised and when the current is the same as when the servo valve is lowered. 3. The flow rate control device for a double hydraulic cylinder according to claim 2, wherein the double hydraulic cylinder is a drive device for reciprocating a punch of a turret punch press.